Tan et al. 2006
USA
PEDro=10
RCT
N=38

Population: Type of pain=mixed
Treatment: Subjects received TCES or sham TCES for one hour for 21 days to treat neuropathic or musculoskeletal pain. Following this, the control group was offered the opportunity to participate in an open-label TCES study.
Outcome Measures: BPI

1. No significant difference between TCES and sham groups for BPI. However, several individual interference items were significantly reduced, from pre to post intervention, in the TCES group only.
2. For active TCES, average daily pain intensity from pre to post assessment decreased significantly (p=0.03) compared to the sham (control) group.
3. Significant reduction in daily pain intensity noted in treatment group (pre-post) (p=0.02) but not in control group (p=0.34).
4. During open label trial, a reduction in pain was noted after TCES treatment (p=0.003)

Fregni et al. 2006
USA
PEDro=9
RCT
N=17

Population: Type of pain=neuropathic
Treatment: Subjects received either sham (10sec of stimulation with same procedure but then turned off) or active tDCS (2mA, 20 min for 5 consecutive days).
Outcome Measures: VAS

1. Treatment produced significant decrease in pain scores over time (p<0.0001).
2. The largest pain reduction was noted after session 5; effect decreased during follow-up, though pain scores remained lower than baseline scores.
3. There was no significant effect of treatment on either anxiety or depression scores in either group.
4. Effects on cognitive function similar for tDCS and sham.

Capel et al. 2003
Canada
PEDro=8
RCT
N=30

Population: Type of pain=mixed
Treatment: SCI subjects randomly assigned to one of two groups. Treatment group received transcranial electrostimulation (TCES) twice daily for 4 days, while controls received sham treatment. After an 8-week washout period, treatments were reversed for sham treatment group only; thus, during the second half of the observation period, all received active treatment. 3 subjects left the study early, 2 because of interactions between TCES and medications.
Outcome Measures: SF-MPQ; STAI; BDI

1. During first part of the study, those on TCES reported less severe pain vs. baseline (p=0.0016); controls reported no change.
2. During phase two of study, control group (now receiving TCES) also reported significantly less pain (p<0.005).
3. Treatment group used fewer medications (analgesics and antidepressants) while receiving TCES (p<0.05).
4. Groups did not differ in pre-morbid psychological states (i.e., STAI, BDI) nor was treatment effect associated with mood in either group.